willbav8r inadvertently touched on the nub of this argument whne he said:
"Surely the higher airspeed with 30 deg flaps as opposed to 40 gives better handling/manoevreability (lift?) in gusty x wind conditions?"
It is not the crosswind that should predicate a reduction in flap but the gusts. In a gustless crosswind, reduced flap will simply extend the float on round-out and is more likely to result in the aircraft leaving the downwind side of the runway after drift has been removed. However, in gusty conditions where windshear is more likely, the benefit of increased response with less flap outweighs the disadvantages after roundout.
We are talking here in terms of light aircraft, not heavy, swept-wing, metal (or swept-wing turboprops???).